1. Field of the Invention
This invention relates generally to semiconductor technology and integrated circuit structures, and more particularly the invention relates to integrated injection logic cells and the method of making same.
2. Description of the Prior Art
Integrated injection logic is a simple form of bipolar logic in which PNP and NPN transistors form a gate with one transistor injecting the base or drive current to control the conductance of the other transistor. In integrated injection logic cells the transistor structures are merged with the injector transistor formed laterally across the surface of a device cell and controlling the conductance of one or more complementary transistors which are vertically oriented in the cell.
Oxide isolated integrated injection logic cells are disclosed in U.S. Pat. No. 3,962,717 to O'Brien, and are discussed by Hennig, Hingarh, O'Brien, and Verhofstadt in "Isoplanar Integrated Injection Logic" Journal of Solid State Circuits, Vol. SC 12, No. 2, April, 1977 pp. 101-9. Inherent advantages of the oxide isolated integrated injection logic cell include reduced size of circuit elements, simplicity of fabrication processes, and low power requirements. However, heretofore a limitation inherent in an integrated injection logic cell having a fanout of two or more is the tradeoff between base resistance and the size of the device cell. More particularly, base resistance has been reduced by increasing the size of the extrinsic base region which also increases the device cell size and attendant capacitance.